An optical fiber with ultra-low attenuation and large effective-area includes a core layer and cladding layers. The cladding layers have an inner cladding layer surrounding the core layer, a trench cladding layer surrounding the inner cladding layer, an auxiliary outer cladding layer surrounding the trench cladding layer, and an outer cladding layer surrounding the auxiliary outer cladding layer. The core layer has a radius of 4.8-6.5 μm, and a relative refractive index difference of −0.06% to 0.10%. The inner cladding layer has a radius of 9-15 μm, and a relative refractive index difference of about −0.40% to −0.15%. The trench cladding layer has a radius of about 12-17 μm, and a relative refractive index difference of about −0.8% to −0.3%. The auxiliary outer cladding layer has a radius of about 37-50 μm, and a relative refractive index difference of about −0.6% to −0.25%. The outer cladding layer is a pure silicon-dioxide glass layer.